The present invention relates to a connecting rod made of fiber reinforced synthetic material. Such rods are, for example, used as crankshaft rods, whereby one rod head or rod end is connected, for example, to a piston bolt by means of a closed cylindrical bearing while the other rod end or rod head is connected, for example, to a crankpin by means of a divided cylindrical second bearing. The second bearing is formed by the divided big end of the rod constructed as a half shell cooperating with a substantially mirror-symmetrically shaped second half shell forming an outer bearing cover bail. These components are held together by a loop of unidirectionally oriented fiber strands looping around the closed bearing cylinder, whereby the fiber strands extend in the longitudinal direction of the rod. The bearing cover bail is secured to the free ends of the loop forming fiber strands.
German Patent Publication (DE-OS) No. 3,004,575 discloses a crankshaft rod of the type described above. The crankpin bearing of such a rod is divided for assembly or mounting reasons. The known crankshaft rod has a core of synthetic material encased by a metal jacket. Such a structure has, compared to a full metal construction, a substantially smaller mass or weight and hence using such crankshaft rods results in an increased or improved quiet run and an improved efficiency of the respective engine, especially if high r.p.m. stroke piston engines are involved. The ideal solution under such operating conditions is to avoid any type of metal components. However, by omitting merely the metal jacket in the prior art crankshaft rod, the result would be, among others, that the required strength relative to compression and tensile forces or stress is not assured anymore. The remaining fiber loop which is only capable of taking up tensile stress would buckle in response to compression stress. Another undesirable feature of such prior art rods which comprise a metal jacket, is seen in that the load distribution is uneven. The metal jacket which functions, among its other functions, as a supporting outer shell of the fiber loop is not fully utilized because the compound or interaction of two materials each having a different modulus of elasticity is not ideal when the crankshaft rod is under load conditions. Under such conditions the stiffer fiber reinforced material is subjected to most of the loads while the supporting outer metal jacket is not fully utilized.
German Patent Publication (DE-OS No. 2,951,112) discloses a cam shaft connecting rod with an endless loop of fiber compound material. Such loop has a layered construction, but does not provide a hint toward an open loop construction because this prior art rod has two closed bearings.